Automatic balancing installation



Aug. 2, 1960 J. F. LAsH AUTOMATIC BAIANCING INSTALLATION NQ @es Ugg Filed Nov. 19, 1954 ATTORNEY and opened relative to a fixed reference point on the crankshaft.

The energizing circuit for relay coil 56 includes conductor 82, a source of power such as battery 84, conductor 86, contacts 70, 72 and conductor 88. The movable switch arm 54 of the relay 48 thus is alternately moved between its contacts 50, 52' to provide a reversing or commutating action of the amplified pickup signal. This commutated signal appears in the output of the unbalance angle relay contactor device 40 between conductors 90 and 92, which are connected to switch arm 54 and the center tap of the transformer secondary winding, respectively, and may be displayed on a zero center D.C. milliammeter 94 connected between conductors 90 and 92. Rotation of the control knob 80 to adjust the position of the cams 66 and 68 with respect to the crankshaft will cause the amplitude of the full wave rectified signal displayed on meter 94 to vary between a maximum negative and a maximum positive reading. The control knob 80 is provided with angular graduations thereon so that its angular displacement relative to a reference pointer 96 on a stationary panel or the frame 918 of the contact mechanism 64 may be read for a zero or null reading of meter 94 as an indication of the angular location of the unbalance in the left end of the crankshaft. While the knob 80 may be adjusted by an operator to elect a null reading of the meter as in an open loop step sequence system, the present invention comprehends automatic positioning of the contact mechanism, as will be brought out later herein.

The amplitude or magnitude of the total unbalance at the left end of the shaft is determined by applying the vamplified pickup signal appearing at the output of ampliiier 34 to a second chopper or unbalance amplitude relay contactor device 100 which is similar to chopper 40 and includes -a transformer 102 having a primary winding 104 and a center tapped secondary winding 106 and a relay contactor 108 with a switch arm 110 movable between a pair of stationary contacts 112 and 114 by an energizable actuating coil 116. Actuating coil 116 is connected in an energizable circuit which includes conductor 118, battery 120, conductor 122, contacts 74, 76 of contact mechanism 64 and conductor 124.

The commutated output ofthe second chopper 100 is taken from the center tapped secondary winding 106 and switch arm 110 and applied as a full wave rectified signal over conductors 130, 132 to a closed loop servo controlled amplitude comparison circuit which automatically indicates the magnitude of the unbalance quantity and positions lan adjustable drill stop setting element 134 of a balance correction drilling organization associated with the unbalance determining apparatus to effect exact compensation for the amount of the unbalance at the left end of the shaft. The amplitude comparison and drill stop positioning apparatus includes a conventional servo amplifier 136 and its associated two-phase servo positioning motor 138 and a potentiometer arrangement comprising the adjustable resistor 140 connected across a fixed, known reference source of balance voltage, shown as battery 142. The output of the second chopper 100 is connected in series with the input of the servo amplifier and the por- Ition of the output of the potentiometer appearing between conductor 132 and the adjustable arm 144 of the potentiometer resistor 140, which is mechanically coupled to the shaft 146 of the servo motor 138.

One of the phase windings of the servo motor 138 is connected for energization from a local alternating current source of supply and the other quadrature phase winding thereof connected for energization by a control signal, which appears at the output of the servo amplifier 136 and corresponds to the amplitude difference between the output of the chopper and the potentiometer. The resulting differential control signal is of such magnitude and polarity as to tend to rotate the unbalance servo motor 138 in a direction and an amount such as to reduce the error or control signal to zero, at which point the amplitude comparison system will be balanced `and the motor or translating device will cease moving.

An indicating arrangement in the form of a graduated indicator dial 150, which may be provided on, say, the stator casing of the servo motor 138, and a pointer 152 carried by the shaft 146 may be employed to indicate the magnitude of the unbalance. The shaft 146 of the unbalance servo motor 138 is directly coupled to the drill depth control element 134 of a balance correcting drilling organization or equivalent balance correcting apparatus, which is mounted under the engine assembly, and adjusts the drill depth setting element vautomatically in accordance with the determination of the magnitude or amount of unbalance. It will be noted that both the unbalance magnitude determination and the setting of the drill stop element are performed automatically without human intervention.

To provide for automatic adjustment of the knob of the contact mechanism 64, the output of the iirst or unbalance yangle relay contactor 40 is applied to the input of a servo amplifier 177 of a servo positioning system, thereby dispensing with this previously manually performed operation. The output of the servo amplifier 177 is connected over conductors 179 and 181 to the variably energized phase windings of an angle positioning servo motor 183 whose rotor shaft 185 is geared to the rotatable housing or knob 80 of the contact mechanism 64.

The apparatus may further include still another servo positioning arrangement for angnlarly positioning the handwheel 20 upon conclusion of the unbalance determining operation to correspond to the extent of rotation of the unbalance angle servo motor 183 when lthe relay contactor 40 was adjusted to balance, and thereby to locatel the crankshaft in proper relation to the balance correctlng apparatus. This last-mentioned crankshaft positioning arrangement may include a synchro transmitter device 187, the rotor shaft 189 of which is coupled to the shaft 185 of the servo motor 183; a synchro receiver device 191 the three-phase stator winding of which is electricallyV connected to the three-phase stator winding of the transmitter device 187 over conductors 193, 195, 197; a servo-amplifier 199 the input terminals of which are connected to the rotor winding of the receiver synchro device 191 over conductors 201 and 203; and a two-phase power servo positioning motor 205 the control phase windmg of which is connected to the output of the servo amplifier 199 over conductors 207 and 209. The other Winding of the servo motor 205 is energized from a local alternatmg current power source. The rotor shaft 211 of this servo positioning motor is coupled through suitable gearing 213 to the wheel 20 or to the crankshaft itself and through gearing 217 to the shaft of the synchro recelver in the manner of synchro-controlled servo positionlng arrangements. A switch 215 may be provided in one of the A.C. source conductors of the position transmitter device 187 and is adapted to be closed to energize this data transmission system at the conclusion of the unbalance determining cycle when the drive motor 16 stops rotating, at which time the control phase winding of the servo motor 205 will be energized to servo position the wheel 20 in accordance with the determined angle of unbalance location for the left end of the shaft.

The two cams 66 and 68 of the contact mechanism 64 both move as the servo motor 183 automatically adjusts the control knob 80 or housing of the contact mechanism 64 for zero or null reading on the D.C. meter 94. The output of chopper 40 associated with unbalance loca.- tion or angle determining portion of the apparatus is then zero while that of chopper associated with the quadrature related cam 68 of the unbalance magnitude determining portion of the apparatus will be a maximum. The unbalance servo motor 138 controlled from the unbalance magnitude relay contactor 100 adjusts the drill stop element 134, and after the drive motor has been stopped; the synchro data transfer system 187, 191 is energized to QnirQl imm.I it-which adjusts` the han@ vvheeig'zol to h. th exposed: counterweight ofrthercraukshaft r j Ori .off-thebalance ccrrectionsistobeperrormed cvs the-1111? 19W tlieasirrev 1 Sii la. .,M., aeahdfentharieh@racailleshafnwitil -1o similar apparatus associated withniclcglp 24. l

ofthe-.Cheap Hiring apparat r the 111i-- balance es d cult a that. tithe py se eiland e t aas afahelas. th th P Sflters M 2o Ricicla 2.4.. 'is atlante@ tossineunbalariceeffestsin il?? richtl andl sfide., 'crankshaft andwill have, i imputan plied t9 an,unbalanedetetraiaina anddrill; depthqntrl ein attismludna a. Secondfcmltact mechanisifnd-sc- Oasis@ 0f` aaslalcaficnand unbaleacemagnitude cha- 25 asd. assoiated PQSitiOHing; apparatus identical with thatyassociate lwithjzgickup 2,2, the complete illustration .f;wh4, .hasbea omitted for simplicity 'of thedrawine While, the present. invention hasfbeen Shown cadde? Saribed @asia as .applied t0. the nnbelance, detevtimad 3o @ses 9.1i ,Qflribalane intr/0 arbitranly Selected. transf axial planes of correction in elongated bodies; Ysuclras raakshatts, it` is, apparent; that thernncirles, arid ap- Patatas Ot-.fhfarrsaeaf iaventifm are'equally adapted, 19 jiitomatiadstecticn-aad @traction of unbalaaceibodies 35 in which the unbalanceris-elocatedin but asinglel trans,- axial plane. l

What is claimed is:

1. Apparatusfon automatically determining` the location of unbalanegof a dynamically unbalanced rotating 40 body comprising in combination vibrationpickup means rteslrron'siveI to, viblliQus, induced by/ unb-alanceflin said bQdy and@ 1912i g. arericdicallyrvarving signalhavt. illlaNiS Lela to.. the location ofrunbalance iisidibQlY; .IiQPR device having an input. circuit couneetedttoL saidvihration pickupmeans and-Lanoutput sirsilltrwitht a .atnmutatcr therein; a.; variable- Contact A1 1,,rechanimsm cpritgqlllfn g,the outputfromsaid chopper de- Vfeiaiflinchldll'ig.Qemdriycntin Synchronismwith said body,1 a nunotswitch ccntactsadapdafc be Iactuante .by said cam and adjustable means for changing the position in space of said switch contacts relative to said cam, said Y switch contacts being connected in circuit controlling relation with said commutator; and servo positioning means connected to said commutator to be responsive to the output of said chopper device for automatically adjusting said adjustable means of said variable contact mechanism so that the output from said chopper device will be some predetermined amount.

2. Apparatus for automatically determining the location of unbalance of a dynamically unbalanced body comprising in combination, oscillatable means supporting the body `for rotation about its axis; drive means including a rotatable shaft coupled to said body for rotating the latter on its axis; vibration pickup means responsive to vibrations'induced in said oscillatable supporting means by unbalance in said body and actuable by said supporting means, said pickup means developing a periodically varying signal having characteristics related to the location of unbalance in said body; a commutating chopper device including a transformer having a primary winding connected to said vibration pickup means and a center-tapped secondary winding, a relay having a pair of stationary contacts connected to the opposite ends of Ysaid secondary Winding and an armature movable between said contacts 75 Yby 'an operating con; of the relay; a varabie. contact mechanism. includinga cam drivenby said: drive means in synchronism with said body, a pair of switch contacts adapted to be. actuatedby-Saidicam and,adjustableV means for changing `the positionin spaceof saidV switch contacts relative. torsaid cam, said switch contacts being conf nected in an energizing circuitfor said relay operating coil; and servo positioning means; connected to receive theou-tpnt` offsaid4 chopper; device constituted by the relav: armatureandcenterftapo said transformer secondary winding for automaticallvactuating saidadjustable of=said variablecontact,K mechanism so that said output will; bei some predeter-mine'd;v amount.

3. The combination in accordance with claim` 2 Iabove wherein saidyservo positioningmeans includes a Servo motor having, a control Winding coupled to said relay armature .andithecenterftap of thetransformer secondary windingand a rotor mechanically coupledto adjust said adjustableJ-meaps. of sfaid variablecontact mechanism.

T4. The combination in accordance with claim 2 above wherein said servo positioning means includes a servo motor havingfacontrol winding. coupled to said relay armature and the centen tappi-the transformer secondary windingandaroton mechanically coupled to adjust said adjustable means of said variablecontact mechanism; and a:data.transmission.systemincludingga synchronous transf mitter element coupled -to the rotor of'said servo motor, a synchronous receiver, element, anda second servo motor havinga Qontrol winding energizedfrom said synchronous receiverA element and a` rotor. coupled Ito saidshaft. of said drive means andto said;rec eive`r element, and means energizingy said.y datai transfer system when said. drive means stops rotating.

5-. ApparatusV fon automatically determining the mag nitude` and locationl ofI imbalance ofla dynamicallyl unbalancedv body-.comprising in combination, oscillatable means.supporting: the body for rotation about`its.. axis; drive means including. a rotatable shaft'coupledf toV said body for. rotating theplatter oni-ts. axis; vibration pickup means. responsive .to vibrations induced. in said oscillatable supporting'smeans by unbalance in said body and developing a. periodically, varying; signal having amplitude and phase. characteristics relatedftotheV magnitude. and location offunbalancein said body;a pair of-commutating chopper devices. each .including a.l transformer `having;v a primary-winding connected to saidgyibrationpickup and a.center.tapped secondary winding, a relay havingya pair` of stationary contacts connectedLtotthe oppositef ends of the position in space of said switches relative to said cams,-

said switch contacts of each of said switches -being connected in an energizing circuit for the relay operating coil of a different one of said chopper devices; a servo positioning means for automatically adjusting said adjustable means of said variable contact mechanism and connected to receive the output of one of said chopper devices constituted by the relay armature and centertap of the transformer secondary winding thereof so as to change the relative position of said switches and cams until the output of said chopper device Vis substantially zero; and a self-balancing type amplitude comparison circuit connected to the output of the other of said chopper devices.

6. The combination in accordance with claim 5 wherein said shelf-balancing type amplitude comparison circuit includes an adjustable known source of 'balancing potential and a servo motor, which is actuated by the difference signal between the commutated output of the other of said chopper devices and said adjustable known source of balancing potential and is operatively connected to adjust the-latter to reduce the ysaid difference signal to zero.

7. The combination in accordance with `claim which includes an adjustable stop element positioned by said servo rmotor in the course of balancing said self-balancing amplitude comparison circuit.

8. The combination in accordance with claim 5 wherein said servo positioning means includes a servo motor having a control winding coupled to said relay armature and the center-tap of the transformer secondary winding of one of said chopper devices and a rotor mechanically coupled to adjust said adjustable means of said variable contact mechanism.

9. The combination in accordance with claim 5 above wherein said servo positioning means includes a rst servo motor having a control winding coupled to said relay armature and the center-tap of the transformer secondary winding of one of said chopper devices and a rotor mechanically coupled to yadjust said adjustable means of said variable contact mechanism 4and wherein said self-balancing amplitude comparison circuit includes an adjustable known source of balancing potential and a second servo motor that is actuated by the dierence signal between lthe commutated output of the other of said chopper devices and said adjustable known source of balancing potential and is operatively connected to adjust the latter to reduce said difference signal to zero.

10. Apparatus for automatically determining the magnitude and location of unbalance of a dynamically unbalanced rotatable body comprising vibration pickup means responsive to vibrations induced by unbalance in said body, said pickup means developing a periodically varying signal having amplitude and phase characteristics related to the magnitude and location of unbalance in said body; a pair of commutating chopper devices each including a transformer having a primary winding connected to said vibration pickup and a center-tapped secondary winding, `a relay having a pair of stationary contacts connected to the opposite ends of said secondary winding and an armature movable ybetween said contacts by `an operating coil of the relay; a variable contact mech- `anism including a pair of switches each having a pair of switch contacts, cam means driven in synchronism with said body and disposed with respect to said switches to actuate -the closing of the respective contacts thereof 90 degrees in time phase apart, and adjustable means for changing position in space of said switches relative tosaid cam means, the said switch contacts of each of said switches being connected in an energizing circuit for lthe relay operating coil of a different one of said chopper devices; a servo positioning means operatively interconnected with said adjustable meansof said variable contact Amechanism and connected to receive the output of one of said chopper devices constituted by the relay armature andvcenter-tap of the transformer secondary winding thereof for automatically adjusting the relative position of said switches and cam means until said output is a minimum; `and a self-balancing type amplitude comparison circuit connected to the output of the other of said chopper devices.

, 11. Anapparatus for determining the unbalance in a rotating workpiece comprising a pickup responsive to vibrations vin said workpiece for creating an unbalance signal indicative of the unbalance in said workpiece, reference means for simultaneously creating a pair 'of 90 angularly disposed components bearing a known but adjustable phase relation to said workpiece, second means interconnected with said reference means for adjusting said phase relation, a circuit interconnected with said reference means and including a pair of separate rectifier portions responsive to said components, each of said portions being eiective to rectify said unbalance signal in response to one of said components to produce a pair of separate electrical output signals, servo mechanism operatively interconnected with said second means and being responsive `to one of said electrical output signals for automatically controlling said phase relation between said workpiece and said reference means so that said last mentioned output signal will be reduced to a minimum and means for -indicating the amount of the other of said output signals.

l2. The combination of claim 11 wherein said servo mechanism also includes means for repositioning said workpiece when it is not rotating to correspond to the adjusted position of said reference means.

References Cited in the tile of this patent UNITED STATES PATENTS 1,822,075 Aronoff Sept. 8, 1931 2,131,602 Thearle Sept. 27, 1938 2,177,830 Janeway Oct. 31, -1939 2,196,039 Thearle Apr. 2, 1940 2,243,379 Johnson May 27, 1941 2,678,558 Pischel May 18, 1954 2,731,835 Hellar et al. Jan, 24, 1956 2,779,217 Stovall et al. Jan. 29, 1957 2,783,649 Hope Mar. 5, 1957 

